FR2461209A1 - ACCUMULATOR FOR THE STORAGE OF HEAT OR COLD - Google Patents

Abstract

ACCUMULATOR WITH CONTAINER FILLED WITH A LAYER OF 48 MELTING BUFFER MATERIAL AT CONSTANT TEMPERATURE AND A LAYER OF HEAT TRANSFER LIQUID 47 WITH LOWER OR HIGHER MELTING POINT THAN THOSE OF SOLID OR LIQUID BUFFER MATERIAL, WITH DISCHARGE LIQUID PORT 49 TRANSFER TO DEVICES EXTERNAL TO THE ACCUMULATOR. ACCUMULATOR CHARACTERIZED BY ONE OR MORE COALESCING DEVICES 50 BETWEEN THE BUFFER MATERIAL 48 AND THE OUTLET PORT 49 FOR THE TRANSFER LIQUID TO STOP PARTICLES OF BUFFER MATERIAL. ACCUMULATOR APPLICABLE TO HEAT OR COLD STORAGE.

Description

2 2461209

  The present invention relates to an accumulator for storing heat or cold. More particularly, it relates to a hot or cold accumulator of the type comprising a container filled to a large extent with a layer of buffer material melting at a constant temperature, and a considerably thinner layer of a heat transfer liquid. melting point lower than that of the buffer material, and having a specific density lower or higher than both the solid buffer material and the liquid buffer material, this heat transfer liquid being immiscible with the buffer material. The container has a discharge conduit for the heat transfer liquid from said

  inner thin film to devices external to the

  emulator, and a supply line to reintroduce the

  heat transfer to the distributing devices in the buffer material layer by forcing the heat transfer liquid to flow upwards or downwards in

  direct contact with the buffer material.

  Such apparatus is described in US Pat. No. 2,996,894, according to which it is expedient to use such a device.

  - accumulator as a cold reservoir for a heat pump.

  The buffer material used is then, for example, water or a eutectic mixture, such as a eutectic salt solution, and the heat transfer liquid is constituted by

  oil. After being cooled externally to the accumula-

  (for example in the heat pump), this oil is

  introduced into the bottom of the accumulator, where it is dispersed.

  The formed droplets rise upward until they reach the oil layer floating on the buffer material, and in their path they exchange their heat with the buffer material which is thus partially frozen. The patent in question specifies that the solid buffer material accumulates

  the heat near the interface of the layers, and this

  cessus can be continued until a mass is formed

  thick paste of solid and liquid buffer material.

  The cold thus stored can be recovered by heating the oil outside the accumulator to above the point

  melting the buffer material and continuing the circulation.

  Due to heat exchange, the buffer material will melt

  then gradually, while the oil will be cooled.

  French Patent No. 1,360,833 discloses a heat accumulator, wherein the exchange between the buffer material and the heat transfer liquid is caused by forcing the heat transfer liquid to float on the buffer material, and stirring vigorously. this by means of an agitator, or by tangentially introducing the transfer liquid into the upper layer. According to this method, the buffer material chosen is a molten salt. If the salt in the solid state is heavier than the molten salt, the exchange of

  heat in this way can only occur in

  shallow, and in all cases agitation requires

significant amount of energy.

  German Offenlegungsschrift No. 2,508,447 describes various models of accumula-

  apparatus, including an apparatus in which a melt buffer material is pumped from the bottom of a container to the top where it is in contact with a liquid or a gas thereof.

  circulating heat transfer.

  - DE - B - ng 1 015 019 and - the patent application holland

  No. 2,704,099 disclose cold accumulators in which the heat transfer liquid, or its vapor, is passed through metal pipes disposed in the buffer material, these pipes serving as heat exchangers. The Dutch patent application also proposes the use of a pump

  during the melting of the solid buffer material with a view to

  cull the molten buffer material through the gap between the pipes and the still solid buffer material. However, because

  the high cost of pipe sets, such an accumulator requires

  investment of significant capital.

  Tests carried out with an accumulator described in US Pat. No. 2,996,894, using, as a buffer material, water or a eutectic solution of salt, and, as a heat transfer liquid, a light oil, and cooling. the transfer liquid in a heat exchanger outside the accumulator itself, have shown that it is impossible

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  to obtain a regular operation with such accumulator.

  In the first place, when the circulating transfer liquid is dispersed in its aqueous phase, a certain

  number of tiny droplets-have been formed that escape

  pent to coalescence, but remain floating in phase

  aqueous. As a result, the volume of the aqueous phase is

  Increasingly, it sometimes reaches the outlet for the transfer liquid. the buffer material in the liquid state then enters the external heat exchanger, in which

  it solidifies, so this heat exchanger is well-

- closed.

  when the disperser is replaced by

  different dispensing media which do not form fine

  In this way, it is found that the drops rise rapidly towards the separation surface between the aqueous phase and the oil phase, and that a mass of crystals is formed on this boundary surface. Even in this case, the heat exchanger is closed with solid buffer material after a certain time, which prevents the continued operation of the apparatus A search for the causes of this disadvantage has shown that when a drop of oil having a temperature below the melting point of the buffer material is formed in this material, this drop absorbs heat from the buffer material, and at the same time a small amount of this material is

  solidified and still contains the drop in the form of a pel-

  slim thin solid. This film is not always complete-

  closed. thin-walled hollow corpuscles of solid buffer material, which are filled with transfer liquid, rise in

  the buffer material and reach a certain speed of displacement.

  maximum effect. When they reach the boundary separating boundary between buffer material and oil, they still maintain the same speed for a certain time and, as a result, they rise

  quite high in the oil layer. Because of their apparent weight

  If they are light, they only descend slowly towards the limit surface, especially since they are delayed in their displacement by the ascending oil current. when these globules which float in the oil (and, in addition, the solid buffer material also frequently contains some buffer material in the liquid state) are transferred at the same time as the oil to the heat exchanger placed at the outside the accumulator, and that they are

  thus additionally cooled, a proportion of these

  bules will settle and eventually clog the heat exchanger. The use of a filter, a sieve or a screen, to hold these globules turns out to be worthless, because the only result is that this filter or sieve is closed with the material

  solid buffer, which appears to adhere securely to the sieve.

  These adverse effects occur even after a mass of crystals is formed on the separating surface between the

  Buffer material and oil. It is true that part of the world's

  they burst through this separating layer, but another portion penetrates through the intact mass and rises in the oil. This happens even when the buffer material is

  virtually completely frozen.

  the American patent and other literatures are

  completely silent about these difficulties, and does not pre-

  feel no way to solve them.

  The subject of the present invention is an accumulator of the type described which is characterized in that it comprises one or more coalescing means for retaining solid and liquid particles of buffer material, these means being provided between the buffer material and the orifice of output for liolid

transfer.

  Coalescing devices are known and self. They smell used to intercept fine liquid-gas droplets

  or other liquids, in which such droplets float.

  A coalescent device consists of a knitted tablecloth of very

  a large number of thin textile or metal wires (a thickness which can be much greater than the

  droplets to be collected), these wires being united in a spatial network.

  the free surface of a coalescing device is commonly equal -

  at 95 to 99% of the apparent surface. The material of textile yarns

  the or metallioues is not critical for its effectiveness, and,

  in practice, uses a material that is inert under the conditions of

  operational requirements. If desired, these wires may be corrugated. It is noted that such a coalescing device is capable of capturing the globules in question without being obstructed. The volume of the seal of the captured cells is often greater than the volume of the

  coalescing device itself. It is to be presumed that globular

  strike them against the wires of the coalescing device, so that the buffer material remains alone behind the coalescing device. Since the oil entering the heat exchanger disposed on the inside of the accumulator is now free of buffer material, the freezing of the buffer material in the accumulator can occur without disturbance. Surprisingly, it is found that the buffer material can be frozen at approximately 99%, while, nevertheless, the oil stream can rise in the form of droplets through the porous mass of buffer material without disturbance, while , on the separating surface, even globules surrounded by

  Solid buffering material can continue to rise. As a result

  this, the buffer material does not condense into a solid block, but into a non-compact porous mass that has many small

  channels, through which oil can rise without difficulty.

  Since the number of droplets that rise

  is very large at every moment, we obtain a very wide surface

  due for the exchange of heat between the oil and the buffer material.

  Thanks to this very large surface, the heat exchange can be

  even in the case of a very small difference in temperature.

temperature.

  When the buffer material is completely or partially

  frozen, the stored cold can be removed from it again

  (or the heat can be restored in him) by now feeding

  oil having a temperature just above the

  melting point of the buffer material instead of cooled oil

  below the melting point. The oil droplets exchange the heat, so that the solid buffer material is melted while the oil is cooled below the melting point in question. Both during the solidification of the material

  buffer and during its melting, the temperature of the oil de-

  charged remains substantially equal to that of the melting point of the buffer material, while in both cases the temperature of the oil fed does not need to differ much from the melting point (for example only 2 degrees), while

  that a large amount of heat can be fed or

  per unit of time in the accumulator.

  This favorable heat transfer is maintained from the beginning of freezing until more than $ 99 of buffer material is frozen. It is only then that the temperature of the discharged oil begins to differ appreciably from that of the melting point. In the same way, during melting, the temperature of the discharged oil remains continuously equal to the melting point, and this temperature only begins to differ markedly after more than 99% of the buffer material has again reached the melting point. liquid state. At that moment, there is a sudden rise in temperature in

the discharged oil.

  During the melting of the buffer material layer, the transfer liquid is cooled just above the melting point of the buffer material. However, it has been found that the transfer liquid is then just hot enough to melt the solid buffer material present in the coalescing device, so that

  this material then flows down again in liquid form.

  to the buffer material layer. the result is that, during the charging and discharging cycles, the device coalesces

is automatically cleaned.

  In accumulators for heat or cold, it is of great importance that stored cold or heat can again be recovered from the accumulator at substantially the same temperature at which it was fed, because otherwise losses would be suffered as a result of the deterioration In the accumulators according to the invention, this ideal is

  approached very closely thanks to the large area of exchange of

  their, the melting buffer material at a constant temperature is selected so that its melting point coincides as much

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  as possible with the temperature at which heat (or cold) becomes available. As a result, heat or

  cold can be stored in the accumulator at the same temperature.

  re, and when heat or cold, or a portion of these

  This is again recovered later, the heat or cold can be removed from the accumulator at essentially the same temperature. Examples of materials melting at a constant temperature are particular substances, of which water is a very used example. However, it is possible to use

other particular substances.

  When the storage temperature is different from 0 degrees, however, it will often be considered whether it is possible to use a mixture of water and one or more salts which melts at a constant temperature. Such mixtures are referred to as eutectic mixtures. Examples of eutectic mixtures are the following aqueous solutions, which are indicated below with the corresponding eutectic temperatures: Concentration T a MgSO4.7 H20 64 - 5.2 KCl 24.6 - 10o7 [4RC1 a22.0 - 15.8 N41 NaCl 30.7 21.2 NaBr 67 - 28 Mg12.6H20 84 - 33 6 CaC126H20 143 - 55 CC2 2 Examples of eutectic mixtures melting above zero degrees:

YOU

  Na3P04. 12H20 66 NaOH.H2O 64 a2 Q2 32 58 Na2S2O3.5H2O 48 Ca (.NO3) 2.4120 47 FeC 1.6H2O 36

3352 36

1Na2C03.12H20 36

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  Na2003. 1 0H 2 O 3 Na 2 SO 4. For higher temperatures, salt mixtures having a desired eutectic composition and melting point will often be used. In any case, it is favorable that the buffer material used has a high latent heat of fusion and does not have a too low specific gravity, because, then, a large amount of heat or cold can be

stored in a given volume.

  The transfer liquid should be liquid at operating temperature and should preferably be liquid at all temperatures which will occur in practice during use of the accumulator. In a heat accumulator for which these temperatures are above the temperature

  of the room, the transfer liquid should preferably remain

  at room temperature because, otherwise, the accumula-

  would be difficult to start. In addition, the transfer fluid

  fert should have a sufficiently low vapor pressure to prevent evaporation losses and the possible risk of

  at all temperatures of use.

  In a large number of cases, a fraction of

  Venable can be found that meets these requirements and is inert relative to the buffer material. Other inert liquids are

also suitable in principle.

  In most cases, a transfer liquid will be selected having a density below the solid buffer material and the liquid buffer material, but it is also possible to use a transfer liquid that is heavier than the buffer material. both solid and liquid. At all times, however, the transfer liquid must be sufficiently fluid in the liquid state to be able to be pumped effectively at the same time.

  temperature of use and to be able to circulate easily through the dis-

positive coalescing.

  The invention is illustrated by the following examples, with reference to Figures 1 to 6 of the accompanying drawings, in which; - Figure 1 is a diagram of a cold accumulator for refrigerated warehouse premises;

  FIG. 2 shows the upper closure plate of the battery

  emulator of the invention used as cooler; Figure 3 shows the head of the heat exchanger; Figure 4 shows another embodiment, and Figures 5 and 6 are cross-sectional views of two.

  embodiments of an accumulator according to the invention.

  Although in these examples, the invention is illustrated by means of apparatus in which heat is stored at

  temperatures below the temperature of the room, it is obvious

  similarly, the invention can be applied for heat storage at a high temperature, provided that the buffer material and the transfer liquid are adapted to

  the desired storage temperature.

  when using a transfer liquid which is heavier than the buffer material, the supply and discharge lines and the distribution means can obviously be adapted to the new situation but do not raise

  problems out of the known art.

  Generally, the solid buffer material and the liquid buffer material will have different densities so that during freezing as well as during thawing, a change in the volume of the buffer material will occur. Such volume changes can be taken into account in the

  design of the accumulator to prevent the separating surface

  between the buffer material and the transfer liquid can reach the level of the outlet port for the transfer liquid. Usually, therefore, a volume must be provided for the transfer liquid amounting to 15-20 g of the volume of the buffer material, while at the top also there must be a clearance space sufficient to avoid the overflow of the buffer material. overfull. This problem is particularly clear if the buffer material is water because the ice formed occupies a higher volume

  11% to that of the water from which it was formed.

  With eutectic mixtures, the difference is usually more

low.

  In addition, the level of the buffer material must be prevented

  to reach the coalescing device.

  Figure 1 shows the use of a cold accumulator

  included in a refrigeration system for a repository

  in which, during the day, food from

  freshly slaughtered animals are continuously introduced

  in the refrigerated compartments. For the cooling of these foods and to compensate for the heat losses caused by the opening of the installation, it is necessary to provide a large amount of cold during the day. During the night, the openings remain closed and once the meat has been completely cooled, a small amount of cold is enough to compensate for reduced heat losses. Accordingly, without the accumulator, it is necessary to provide a large compressor, for installation, to provide a large amount of cold during the day, but it is not necessary for the night, so that the compressor runs at full capacity only for a relatively short time, about 8 hours a day. Using an accumulator of sufficient capacity and applying an approximately equal storage temperature

  to that of the air circulating in the room, it is possible to

  freeze the battery during the night and take the cold during the day to compensate for the losses. As a result, in

  In this case, the compressors provide a part of the cold required.

  and the accumulator provides the rest. It is then sufficient - to provide a compressor with a capacity equal to about 1/3 of that to be expected in an installation without a cold accumulator0 It is even possible not to use the compressor during the day. Just then predict a larger accumulator. Figure 1 shows a compressor 1 for a refrigerant such as ammonia, refrigerants 3 for compressed ammonia, and a separation vessel 2, wherein the liquefied ammonia is separated from that remaining in gaseous form. This ammonia

  gaseous and returned to the compressor 1 through the pipes

  sented. From the separator 2, the liquid ammonia is passed through the valve 6 to the refrigeration cells 7,

  o Ammonia is vaporized, giving up its cold, and returning

  then to the separator 2 and the compressor.

  When the compressor has a large capacity, greater than that required to provide all the required cold, the amount of liquid ammonia in the separator increases and the pressure is reduced accordingly. A pressure sensitive device

  is provided to connect the accumulator to the cooling.

  The accumulator shown in FIG. 1 comprises a tank 14 provided with a coating layer of insulating material (not shown). Inside the tank is placed a layer

  buffer material 15, which in this case is a eutectic solution.

  only salt. Above this buffer material is provided a layer 16, consisting of a petroleum fraction, for example kerosene. The tank 14 is closed at its top by a plate 21 provided with an eccentric circular opening. Around this

  opening is provided a flange 22 having a series of ori-

  fices 23 regularly spaced, a ring channel remaining open

  between the flange and the wall of the tank 14.

  Figure 2 shows a plan view of this plate. The flange is intended for discharging the transfer liquid

  without turbulence, despite a variable level of the liquid. In the-

  eccentric circular groove, inside the flange 22, is mounted a coalescing device 17 which closes completely

the opening.

  Just above the plate 21 is a pipe

  24 which connects the accumulator itself to a sample of

  heat exchanger 18, of a type known per se, in which the transfer liquid gives up its heat or its cold to a refrigerant, which in this case is ammonia. In the example shown, this heat exchanger consists of a falling film evaporator, in which the transfer liquid flows along the outer wall of a bundle of vertical tubes and, from there, returns to the accumulator through a pipe 25 and a pump 19. The head

  of the heat exchanger 18 is shown in FIG.

  From a dispenser 26, the liquid ammonia is thrown against a spherical plate and then falls onto a dispensing plate 27 provided with small perforations. On this dispensing plate a layer of liquid remains permanently, so that a steady stream of liquid ammonia falls from perforations on a pipe plate 29, where it flows as a uniform film along the pipe wall 30. As mentioned above, the wall

  outside of the pipes is in contact with the trans-

  which is thus cooled and transports the cold to

  emulator. When the cooling phase is interrupted by the pressure sensitive cut-off device, a magnetic valve 12 is closed and magnetic valves 13 and 11 are opened, and the pump 19 is turned on. From the separator 2, the liquid ammonia then flows to the tank 20, in which the level rises accordingly. As soon as the liquid is at a sufficient level, the level regulator 9 turns on the pump 8, the liquid ammonia is pumped through the valve 11 to the distributor 26. The ammonia is vaporized and the transfer liquid carries the liquid. cold to the accumulator. The ammonia vapor returns to the tank 20 and exits through a pipe

to the separating container 2.

  The cooled transfer liquid now passes through line 25 and pump 19, to the accumulator in

  which it is brought, through a dip tube, under a distribution

  conical scorer, at the bottom of the tank 14. The

  scorer used in this invention consists of a plate

  drilled, preferably of metal such as steel, having a series of small holes through which the liquor is distributed in the buffer material. The distributor represented

  in Figure 1 has a large number of holes (not shown).

  0.6 mm in diameter, the area between perceptions constituting approximately 14% of the colonic surface.) It results that rather large drops of oil rise through the eutectic mixture. For example, drops of 3 to 4 mm in diameter Due to the large number of these drops, the heat exchange surface is very large (from 300 to 500 m2 per cubic meter of

  particulate material). In this way, we obtain a very good

2 4 6 120 9

  partition of the transfer liquid by requiring only a very

  low pumping energy. In fact, such pumping energy

  would eventually be used to heat the liquids, which

  would reduce the performance of the cold accumulator. In the case of a heat accumulator, this disadvantage

by the way, not

  In the evaporator 18, the transfer liquid is

  cooled to a temperature below the eutectic temperature.

  When this liquid rises in the form of drops in the tank 14, a film of solid buffer material is formed around it

  of each drop. Most of the solid material is

  seems in the vicinity of the boundary surface of separation between

  layers 15 and 16, but a portion adheres to the

  coalescent tif 17 -No trace of solid material is present above the coalescing device.

  The temperature of the transfer liquid discharged through the conduit 24 is substantially equal to the eutectic temperature

of the mixture.

  the temperature difference is usually lower

  at 0.2 C, and this difference is maintained until

  all the buffer material above the distribution

  scorer 31 has become solid. Then the temperature difference

  ture is growing rapidly, which is a signal for

  the cooling of the accumulator.

  When the refrigerant cells 7 consume more cold than the compressor 1 is able to supply, the pressure in the separation vessel 2 increases. This can be used

  as a signal to start defrosting the accumulator.

  Of course, this operation can also be triggered

  when the battery is only partially frozen.

  For defrosting, the magnetic valves 11 and 13 are

  closed and the pump 19 is restarted. the liquid of trans-

  The fertilizer now arrives in exchanger 18 at a vir-

  the eutectic temperature, for example slight

  lower than the boiling point of the ammonia in the separation vessel 2 and in the container 20 which is

  logged. As a result, ammonia will condense on the surface.

  bottom face of the pipe bundle 18 and flow down while, at the same time, ammonia gas will flow upwards from the container 20 and will also be condensed. The transfer liquid is thus heated and is pumped back to the accumulator 14, in which it abandons its absorbed heat to the buffer material, thereby causing its melting. During this process, the transfer liquid is again cooled to a temperature just above the eutectic melting point, and flows through the oalescent device for

  return to the heat exchanger 18. In the coales-

  hundred, the transfer liquid gives up a little heat

  any solid buffer material that may be present, the

  traitor to melt and flow down. As a result, the coalescing device is automatically cleaned from

any solid material.

  The liquefied ammonia is collected in the vessel 20 and is periodically pumped (controlled by the level regulator), and brought back through the valve 20 to the vessel 2, where it

  is available for refrigeration cells 7.

  Again, the temperature difference between the transfer liquid discharged through line 24 and the temperature

  Eutectic remains virtually constant and less than 0.220.

  This difference in temperature will suddenly increase as soon as the

  all of the buffer material will have melted. This sudden increase in temperature can be used as a signal for termination

  the de-icing process of the accumulator.

  Although FIGS. 1 to 3 show an example embodiment in which, during the deicing process, the

  Transfer liquid first gives up its cold to refrigeration

  such as ammonia, it is of course also possible to pump the transfer liquid itself to the cells 7 and

to use it as a refrigerant.

  A great advantage of the accumulator of the invention lies

  in that such a small difference in temperature between the liquid

  of transfer and the buffer material is sufficient to substantially produce complete heat exchange. So that this advantage

  not be lost, it is highly desirable that the other

  1 4 heat exchangers used in the installation also operate the best possible heat exchange with a small difference

temperature.

For this reason, the falling film evaporator known per se is used in the example described above, which, from this point of view, is very favorable. Other heat exchangers

  of comparable characteristics can of course also be

used.

  FIG. 2 shows an application of the accumulator according to the invention which can be used as a producer

of ice.

  In breweries, sweet drink factories,

  dairies and the like, it is frequently necessary to cool

  quickly give a given amount of liquid that has been prepared at a higher temperature, down to a low temperature, by

  example at 52C. In order to avoid the need to install a

  presser & large capacity, it is commonly used in

  such industries, an ice producing apparatus that consists.

  in a container filled with water and equipped with a large number of tubes inside which ammonia can be evaporated. This results in an ice layer formed on the outer surface of the tubes. In this way, it is possible to store a significant amount of cold. If it is desired to use this cold, a current of water is circulated through the ice producing apparatus, and through the spaces or containers to be cooled which are cooled as a corresponding quantity

  ice cream is melted in the appliance.

  However, such ice makers are expensive to invest. They require filling with a large amount of refrigerant. In addition, the cold is not absorbed or delivered very quickly, which requires other expenses, such as

  only for agitators in the ice machine.

  FIG. 4 represents a battery similar to that of FIG. 1. the main difference lies in that, in

  this case, we use. water instead of the eutectic mixture.

  As in Figure 1, a refrigerant, usually ammonia, is compressed by a compressor 41, liquefied in a

  cooler 42, expanded in a valve 43, and then used

  in a heat exchanger 44 to cool a liquid of

  transfer, for example a fraction of oil, up to

  below 02C, for example at -22C. This liquid of trans-

  The pump is fed to the dispenser by a pump 45 and rises in the form of drops through the water into the accumulator which is thus partially frozen. The transfer liquid heated to 0 ° C is then pumped back into circulation so that all the water present in the accumulator above the dispenser can be frozen, first of all in a mass.

  of crystals and then into a semi-solid porous mass.

  A second difference with the accumulator of FIG. 1 is that the accumulator of FIG. 1 is such that the distributor is not placed exactly at the bottom of the apparatus,

  but slightly higher so that there is always a quantity

  - liquid water below the dispenser without being able to

pumped immediately.

  From this lowest part of the device,

  the water can be pumped by a pump 52 to the refrigeration equipment.

  to manage, indicated schematically by the zig-zag line 51. To retain any drop of transfer fluid which could be possibly entrained, a special coalescent device 50 is

  just ahead of the pump. The amount of transfer liquid

  So collected fertility can move upward in a ccnaduit

  vertical up the accumulator.

  From the external device 51, the water which has been heated is returned to the accumulator for refurbishment. In this sample, the water is dispersed in the liquid layer of

  transfer after it has given up its cold at the primary naisse

  of buffer material. As a result, the transfer liquid is then heated up to about 0 ° C, so that any ice remaining in the melting device is melted by contact with the heated transfer liquid flowing to the liquid. low. the heated water can then be brought back to a point above the coalescing device, so that the

  cleaning of the latter takes place even more quickly. How-

  it is not preferred when the heated water has been

2 2461209

  dispersed in the transfer liquid, it falls downwards and then comes into contact with the ice floating on the separating surface between the water and the transfer liquid. This causes a melting of the ice and cooling of the water again

at OOC.

  According to the present invention, a given volume of accumulator provides a storage capacity much larger than that of a conventional refrigeration apparatus, because no volume is occupied by pipes and remains free for the circulation of the water or its agitation. The rate of absorption and delivery is considerably higher because the drops of transfer liquid have a much larger surface than can be obtained by tubes and the heat or cold need not be passed. through a thick layer of ice. Finally, we save the high expense included in the construction of a bundle of tubes. Previous refrigeration appliances have always been practically built

  in rectangular shape more expensive.

  when water is used as a buffer material, it has been found that the amount of ice to be collected by the coalescing device is considerably greater than when an eutectic solution is used. The case has not been clearly clarified.

  For the sake of safety, provision may be made for a second

  tif coalescent below or above the first. It is thus undoubtedly avoided that ice is deposited in the heat exchanger 4. In the example of Figure 4, the stored cold is discharged in the form of water having a temperature of about 02C, but it is also It is possible to predict that the cold discharged from the ice accumulator is in the form of a suspension of ice crystals in the water. In this case, we obviously do not foresee

  coalescing device in the transfer line of this suspension.

  which is pumpable to a concentration of 60 to 70% ice crystals. These crystals can then be melted to

  the place of the articles to be refrigerated where a time

  lower temperature and more efficient use of the cold

28246 1209

  stored. Refrigeration with a suspension of ice crystals in a water immiscible liquid, such as toluene, is already known per se from US Pat. No. 3,869,870, and US Pat. No. 3,247,678 discloses a method of refrigeration with a suspension of ice crystals in brine. But no practical method has yet been realized for a simple and reproducible manufacture, with a concentrated pumpable suspension of ice crystals in water, without these crystals having

  tendency to grow in large aggregates.

  However, according to the present invention, this is

possible without any problem.

  It is also possible to use a eutectic brine as a buffer material in an accumulator according to FIG. 4, and then to pump this brine or solid eutectic suspension into the brine up to the location where the heat must be unloaded. In this case, the device coalesces

must obviously be deleted.

  Figures 5 and 6 are cross-sectional views of two examples of a cold accumulator according to the invention capable of supplying cold water, the water, after being heated, being returned to the accumulator. In these two figures, the identical component parts are designated by the

same references.

  A heat transfer liquid, cooled externally to the accumulator in a refrigerator up to below 02C,

  for example at -220, is fed through a connection 50 and divide

  The drops are dispensed by distributors 54 which comprise a perforated metal plate, these drops having a diameter, for example 2 to 4 mm. This transfer liquid absorbs heat from water 48 present in the accumulator, which is thus cooled, and finally frozen to form a mass of fine ice crystals. The drops that rise are collected over the

  boundary surface of separation between the water 48 and the liquid layer

  47, all the entrained crystals being retained by the coalescing device 17. From point 24, the liquid of

  transfer is brought back to the refrigerator (not shown).

  If it is desired to remove cold water from the accumulator, it is discharged through the connector 50. In FIG. 5, this connection terminates in an annular channel provided inside the accumulator near its end. background. The top of this channel is formed by a coalescent annular band 59. In FIG. 6, the fitting terminates beneath a square plate coalescing device 59 enclosed within a tube that closely surrounds it. . In both cases, the discharged water 50 must therefore first flow through the coalescing device. Any drop of transfer liquid that would be entrained would be

retained by the device.

  These drops are grouped together and escape from the

  coalescing device under the effect of the difference in gravity.

  The discharged cold water can then provide cold externally to the accumulator and thus be warmed. The reheated water * is dispersed again in the layer of liquid-heat exchanger by the distributor 53. the drops formed fall and arrive in the water layer 48, which contains at its upper part a mass of ice crystals . These crystals are melted and the water is thus cooled. This circulation can be continued until all ice is melted and the

  temperature of the discharged water 50 increases above 02C. Pen

  the collection of cold, the supply of cold by means of

  liquid heat exchanger can be continued without objection.

  Since, when the water is frozen, the volume of the ice formed is greater than that of the water, the boundary area between the water layer 48 and the transfer liquid layer will move upwards. during the process of cooling the accumulator, which leads to the risk of overflow overflow. To avoid this risk a compensation device

  is provided in the apparatus shown in Figures 5 and 6.

  In FIG. 5, this compensation device is a

  vertical tube 56, placed centrally inside the accumula-

  cylindrical and connected to the top, airtight

  on the roof of the accumulator. The bottom end of this tube is.

  - provided with one or more openings 64. On the roof of the accu-

  A supply conduit 57 is connected for a pressurized gas, such as nitrogen or air, provided with magnetically controlled inlet and outlet valves. If desired, a pressure gauge, or a pressure sensitive probe can be mounted there. Another probe 58 is provided inside the accumulator to give a signal as soon as the level of the liquid heat exchanger reaches above or

  below a predetermined threshold level.

  Air is then supplied or withdrawn through the duct 57, by means of an auxiliary device with automatic action, known per se and not shown, so that the water level is at a minimum. The inside of the tube 56 goes up or down and the level of the probe 58 rises or falls in correspondence. Because the level difference inside and out

  of the tube depends on the amount of water that is in the frozen state.

  Here, the pressure in the tube is a measure for this amount of frozen water. After calibration, this quantity can be read either at the top of the accumulator or at any other

  using means known per se such as a remote device

  metric. In the case of the horizontal accumulator shown in FIG. 6, the compensation device is of slightly different construction. This accumulator is a horizontal cylinder

  placed with a slight-slope on feet 66 and provided, to his -

  highest end, of a lady-shaped housing, containing

  among others, a coalescing device 17.

  At its lower end, the accumulator is provided with a separating partition 63 fixed air-tight to the circumference of the cylinder, one or more openings 64 provided near its lower edge. In this way, a compensation chamber is formed at this end and it has the same function and the same functioning as the free epace

  provided inside the tube 56 in FIG.

  Figures 5 and 6 also include a number of viewing windows 60, which have been used in developmental studies. In a current production model, such windows are not needed. Figure 6 also shows a level gauge glass 61 for observation of the liquid level

  in the accumulator during filling or emptying.

  When the accumulator is completely defrosted, the compensation chamber must contain a volume of gas at least equal to the volume increase produced when all the water present is frozen. It is then possible to maintain constant

  at every moment the liquid level in 58. As long as the accumu-

  substantially contains the correct amounts of water and transfer liquid, if an automatic control of the supply and discharge of gas through the connector 57 is used,

  this amount of gas will automatically be brought in when the

accumulator is started.

  Since, when water is circulated

  externally to the accumulator, there is always the possibility that a portion of the water is lost by leaks, or the like, it is desirable to provide a probe 62 in the accumulator at the location of the separating boundary surface between the water layer and the transfer liquid layer. By means of such a probe, it is possible to control, either when the accumulator is totally frozen or completely thawed, if the level still has the required height, and, if necessary, to complete the filling with water. In this case, too, if

  this probe can be connected to an automatic device.

  tick that can either deliver a signal or trigger

necessary corrective measures.

  It is clear that the apparatuses shown in FIGS.

  5 and 6 can be used in an absolutely similar manner if, instead of water, a eutectic mixture is used, and if the liquid phase is circulated externally to the accumulator. If it is desired to circulate a mixture of liquid phase and solid phase, and thus carry a greater number of frigories per unit volume, in an apparatus of this

  type, the suspension will naturally be unloaded directly

  below the separating boundary area of the aqueous phase 46 and the transfer liquid layer 47, i.e.

  - collect the solid phase. In such a case, the liquid phase

  fairy will be brought to the bottom of the accumulator. In addition, in this case,

22 2461209

  no coalescing device will be provided in the circulation line and it will be preferable to temporarily stop the

  pumping the cooled heat exchanger liquid.

23 2461209

Claims (6)

-R E V E N D I C AT IO N S-   1. Accumulator for storing heat or cold, comprising a container (14) filled to a large extent   with a layer (15) of buffer material melting at a temperature of   and a substantially thinner layer (16) of a heat transfer liquid having a lower melting point than that of the buffer material, and having a specific gravity lower or higher than that of the buffer material at the same time. liquid state and solid state, this transfer liquid being immiscible with the buffer material, container comprising a conduit (22) for discharging the transfer liquid, from this thin layer to devices external to the accumulator, and a feed conduit (25) for returning the transfer liquid to a dispenser in the layer of buffer material, constraining it to flow up or down in direct contact with the buffer material, characterized in that it comprises one or more coalescing devices (17) between the buffer material (15) and the outlet fitting (22) for the transfer liquid to retain the solid particles and buffer material liquids.   2. Accumulator according to claim 1, characterized   in that the supply duct (25) for the liquid   of heat transfer is connected inside the accumu-   distributor (26) comprising a plate (27) for   view of a large number of holes with a diameter of 0.4 to 1.0 mm.   3. Accumulator according to claim 1, characterized   in that the distributor is constituted by a plate conical.   4. Accumulator according to claim 1, characterized   rised by a discharge conduit (50) for the liquid buffer material, disposed near the bottom of the container, and a supply conduit (65) for the heated liquid buffer material, disposed at the top of the container.   5. Accumulator according to claim 1, characterized   fed by a discharge conduit (24) for a suspension of solid buffer material in a liquid buffer material in the upper half of the container, and a feed pipe 2461209   (55) for liquid buffer material near the end bottom of the container.   6. Accumulator according to claim 1, characterized   by a clearing house (56), the lower part of which   the upper end comprises means (57) for introducing a gas into the compensation chamber in a manner controlled   when the liquid in the accumulator is at a lower level   a predetermined limit value, and means for discharging gas from the compensation chamber, in a controlled manner, when the level of the liquid in the accumulator   is above a predetermined limit.